A Cochrane review included 6 studies with a total of 658 subjects. No significant differences were demonstrated between the two delivery methods in terms of need for hospital admission (RR 1.00, 95% CI 0.63 to 1.59; 1 study, n=400), change in oxygen saturation (SMD -0.03, 95% CI -0.39 to 0.33; 2 studies, n=120), peak expiratory flow rate (SMD 0.04, 95% CI -0.72 to 0.80; 2 studies, n=90), clinical score (WMD 0.00, 95% CI -0.37 to 0.37; 1 study, n=20), in terms of need for additional treatment (RR 1.18, 95% CI 0.84 to 1.65; 3 studies, n=552), or regarding change in heart rate per minute (SMD 0.09, 95% CI -0.24 to 0.42; 3 studies, n=140).
Comment: The quality of evidence is downgraded by indirectness (lack of data on clinically important outcomes) and by imprecise results (few patients and wide confidence intervals).